Production system and method

ABSTRACT

In a first aspect, systems and methods for producing biodiesel fuel include a modular production unit incorporated onto a single platform or into a housing for ease of relocatability. The modular production unit preferably includes a mixing unit, a reactor unit, a separation unit, a distillation unit, and a filtering unit, all incorporated onto or into a self-contained platform or housing that is able to be easily relocated. In a second aspect, the modular production unit is combined with additional fixed and/or relocatable components to provide a biodiesel processing plant. In a third aspect, a raw materials processing system and method includes a roller barrel adapted for recovery, transportation, and introduction of recycled oil feedstock into a biodiesel manufacturing process. The raw materials processing system preferably includes a hot box for filtering and heating the raw recycled oil feedstock.

RELATED INFORMATION

This application is a continuation of application Ser. No. 10/098,737,the disclosure of which is expressly incorporated herein by reference.

FIELD OF THE INVENTION

The invention primarily relates to systems and methods for manufacturingand processing fuels and, more particularly, relates to systems andmethods for manufacturing and processing biodiesel fuels comprising aself-contained production unit that is capable of being relocated asneeded.

BACKGROUND OF THE INVENTION

Biodiesel is the name for a variety of ester-based oxygenated fuels madefrom vegetable oils, fats, greases, or other sources of triglycerides.It is a nontoxic and biodegradable substitute and supplement forpetroleum diesel. Even in blends as low as 20% biodiesel to 80%petroleum diesel (B20), biodiesel can substantially reduce the emissionlevels and toxicity of diesel exhaust. Biodiesel has been designated asan alternative fuel by the United States Department of Energy and theUnited States Department of Transportation, and is registered with theUnited States Environmental Protection Agency as a fuel and fueladditive. It can be used in any diesel engine, without the need formechanical alterations, and is compatible with existing petroleumdistribution infrastructure.

As reported in “Biodiesel: On the Road to Fueling the Future,” (NationalBiodiesel Board 2001), the disclosure and subject matter of which ishereby incorporated by reference in its entirety, most biodiesel isproduced by the process of acid or base catalyzed transesterification.The transesterification process is a low temperature (150° F.), lowpressure (20 psi) reaction having a high conversion factor (e.g. 98%)with minimal side reactions and reaction time. The general process isshown in FIG. 1, which is based upon a similar figure shown on page 11of the above-cited National Biodiesel Board article. A fat or oil isreacted with an alcohol (such as methanol or ethanol) in the presence ofa catalyst to produce glycerin and alkyl esters, the latter of whichcomprises biodiesel. The alcohol is charged in an excess stoichiometricamount to drive the reaction and is recovered for reuse. The catalyst istypically sodium or potassium hydroxide which is mixed with the alcoholprior to the transesterification reaction. The biodiesel is separatedfrom the glycerin. Variations, improvements, and modifications of thisgeneral process are described in several patents, including U.S. Pat.No. 5,424,467 entitled “Method for Purifying Alcohol Esters,” issued toBam et al. on Jun. 13, 1995, and U.S. Pat. No. 6,174,501 entitled“System and Process for Producing Biodiesel Fuel with Reduced Viscosityand a Cloud Point Below Thirty-two (32) Degrees Fahrenheit,” issued toNoureddini on Jan. 16, 2001, the disclosures and subject matters ofwhich are hereby incorporated by reference in their entireties.

Conventional biodiesel production systems are based upon large, fixedbase plants which require expensive capitalization and on siteconstruction. For example, in order to generate an economically viableamount of biodiesel product, a conventional biodiesel plant containslarge, batch-type reactors, large separation units (e.g., decanters,centrifuges, clarifiers), and distillation columns as tall as 50 to 200feet or more. As a result, current biodiesel production is limited todiscrete locations where fixed plants may be constructed. This resultsin inefficiencies that may otherwise be obtained by locating a plantnear a source of raw materials, or near an end user of the biodieselproduct. Further, the conventional process relies upon batch processing,in which the transesterification reaction proceeds in at least twomulti-hour stages and in which the separation processes are not able tobe performed continuously.

SUMMARY OF THE INVENTION

The present invention was created in order to solve the above problemsassociated with large, fixed base plants that are conventionally used toproduce biodiesel, other fuels, and other products. A primary object ofthe present invention is to provide a preassembled, transportable,modular production system capable of producing relatively largequantities of biodiesel. In the preferred embodiments, the describedproduction systems are capable of producing biodiesel at a rate of about1 million to about 3 million gallons per year. While the systems andmethods are described herein in specific relation to the production ofbiodiesel, those of ordinary skill in the art will recognize that theadvantages obtained by these systems and methods may be applied to theproduction of other fuels and other products as well.

In a first aspect, a preferred biodiesel manufacturing and processingsystem and method includes a preassembled, modular production unit that,in a preferred form, includes the following system components:

-   -   a. a mixing unit;    -   b. a reactor unit;    -   c. a separator unit;    -   d. a distillation unit; and    -   e. a filtering unit. The above components of the modular        production unit are preferably incorporated onto a single        platform, such as a skid mount, or into a housing, such as a        standard ISO Intermodal Shipping Container, such that the system        is easily shipped or transferred to a remote site by either        truck, rail, ship, or other means of transportation. Thus, each        component and the overall system are designed to address the        constraints of limited space availability, while at the same        time providing for maximum throughput and processing of the        widest variety of feedstocks into fuel products.

The basic biodiesel reaction of converting organic oils into alkylesters (biodiesel) and glycerin involves the reaction of a raw oil withan alcohol (typically methanol or ethanol, although most alcohols can bemade to work) and a catalyst (typically sodium hydroxide or potassiumhydroxide). The equipment used for this process generally consists oflarge reactor tanks with paddle type mixers in steam jacketed tanks. Thealcohol and the catalyst are mixed first, then the alcohol/catalystmixture is mixed with the raw oil and allowed to react.

One challenge for the modular production unit of the present inventionwas to create an alcohol/catalyst mixer and a separation reactor thatcould both mix and heat within the space constraints of the modularunit. This is accomplished according to a preferred embodiment of thepresent invention by replacing the conventional top mounted mixers witha pump driven set of nozzle jets within a hot water jacketed tank. Thejets circulate the reactants at a high velocity, and the reactants aredrawn from a cone-shaped bottom portion of the tank for recirculation.This creates a central vortex within the reaction tank that allows rapidand complete mixing of the reactants. The pumps are also used forfilling and emptying the alcohol/catalyst mixer and the separationreactor. A venturi valve couples the alcohol/catalyst mixer with theseparation reactor to allow the constant introduction of the correctproportion of alcohol/catalyst to raw oil.

Once the reactants are thoroughly mixed the reaction begins and the rawoil begins to separate into biodiesel and glycerin. As the glycerin isformed the reaction approaches equilibrium and begins to slow, andeventually stops before all of the raw oil has been reacted. Theconventional practice is to allow the reactant to reach saturation, drawoff the glycerin (with excess alcohol), and then rereact the remainingmixture of raw oil and biodiesel. This process generally takes four tosix hours. By using the alcohol/catalyst mixer and the separationreactors in the manner provided by the present invention, the process issped up to occur within two hours. As glycerin is formed it drops to thecone-shaped bottom of the separation reactor. As part of therecirculation of the reactants, the reactants are run through an array,preferably three, of serial centrifuges to separate the glycerin fromthe raw oil and biodiesel. The raw oil and biodiesel are recirculated tothe separation reactor and the glycerin is sent to a continuous flowdistillation unit where excess alcohol is removed. The excess alcohol isreturned to the alcohol/catalyst mixer, mixed with additional catalyst,and then reintroduced through a venturi coupling into the separationreactor. The entire process is conducted under a constant temperature ofjust under the boiling point of the alcohol (in the case of methanol,just below 150° F.) to speed up the reaction. By maintaining constanttemperature and removal of the glycerin as it is formed, the entirereaction is driven to completion in a much shorter time.

In the preferred embodiment, the alcohol/catalyst mixer and separationreactor comprise tanks made of epoxy coated steel, or entirely instainless, or some combination of the two. The tanks can also beinsulated to retain heat. The number and size of flow jets can be variedto optimize the creation of a mixing vortex, and the direction angle canbe varied in the same manner, and/or optimized for Coriolis efficiency(counter clockwise in the Northern Hemisphere, and clockwise in theSouthern Hemisphere). Further embodiments include embeddedinstrumentation for monitoring temperature, PH, flow rates and volumes,and fill levels.

Although several advantages are obtained by providing the systems andmethods described herein in a self-contained, modular production unit,those skilled in the art will recognize that one or more of thedescribed system components may be provided in a scaled up form for usein a fixed base, nonmodular configuration to obtain the other advantagesprovided by those components.

In a second aspect, the modular production unit described above iscombined with additional fixed and/or relocatable system components in abiodiesel processing plant. In a preferred form, the plant is providedwith components and functionality to provide raw materials processingand finished biodiesel product processing. In particular, the rawmaterials processing includes filtering and separation functionality toremove waste and particulate matter from recycled triglycerides startingmaterials. Further, the finished biodiesel product processing includesfiltering and separation functionality to remove water impurities fromthe finished biodiesel product.

In a particularly preferred form, the raw materials processing andfinished biodiesel product processing systems are co-located on a singleor double transportable platform, such as a skid mount, or in atransportable housing, such as a standard shipping container. In thismanner, similar to the modular production unit described herein, the rawmaterials and finished product processing systems may be relocated to adesired site.

The biodiesel processing plant is preferably provided with additionaloptional components, including storage tanks, spill areas, and/or othercomponents that may provide auxiliary functionality to the plant.

In a third aspect, a raw materials processing system and method isprovided. The preferred system and method is particularly adapted forhandling recycled oils, fats, and greases as feedstock for themanufacturing and processing systems and methods described herein. In apreferred embodiment, a roller drum is provided for collecting andtransporting recycled oil. The roller drum is preferably small enoughfor handling (e.g., 30 gallons or less), and is provided with wheelsattached to the drum by an oversized frame. A removable lid is providedwith a bung hole for inserting the recycled oil.

The roller drums are preferably used with a novel hot box that is usedto filter and heat the recycled oil feedstock for use in themanufacturing systems and methods. The hot box is provided with afiltering capability and a heat exchange capability to perform thesefunctions. The hot box is constructed in a manner that allows the rollerbarrels to be tipped and self-supported in place to remove theircontents into the hot box.

The systems, methods, and apparatus of the present invention will bebetter understood by reference to the Detailed Description in connectionwith the Drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow diagram showing a prior art process for producingbiodiesel.

FIG. 2 is a schematic diagram illustrating a preferred modularproduction unit in accordance with the present invention.

FIG. 3 is a schematic diagram illustrating a preferred biodieselmanufacturing plant incorporating the modular production unit of FIG. 2.

FIG. 4 is a schematic diagram illustrating the process flow of apreferred biodiesel manufacturing process, in flowchart form.

FIGS. 5A, 5B, and 5C are a side view, a top view, and a bottom view,respectively, illustrating a preferred roller drum in accordance withthe present invention.

FIGS. 6A and 6B are a perspective view and a top view, respectively,illustrating a hot box in accordance with the present invention.

FIGS. 7A and 7B are a side view and a cross-sectional view,respectively, of a preferred cone-shaped bottom tank in accordance withthe present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred embodiment of the biodiesel manufacturing and processingsystems and methods of the present invention will be described inreference to the drawings. Turning first to FIGS. 2 and 3, the presentinvention provides a preassembled, modular production unit 10 that, in apreferred form, includes the following system components:

-   -   a. a mixing unit;    -   b. a reactor unit;    -   c. a separator unit;    -   d. a distillation unit; and    -   e. a filtering unit.        The above components are preferably incorporated onto a single        or double platform, such as a skid mount, or into a housing 50,        such as a standard ISO Intermodal Shipping Container, such that        the system is easily shipped or transferred to a remote site by        either truck, rail, ship, or other means of transportation, or        operated in place while situated on a truck trailer, rail car,        or ship. Thus, each component and the overall system are        designed to address the constraints of limited space        availability, while at the same time providing for maximum        throughput and processing of the widest variety of feedstocks        into fuel products.

The preferred mixing unit is an alcohol/catalyst mixer 22 that receivesthe alcohol and catalyst as feeds and mixes the two prior to supplyingthe mixture to the reactor unit. In the preferred embodiment, thealcohol is methanol, and the catalyst is sodium hydroxide, althoughthose of skill in the art will recognize that other alcohols andcatalysts are suitable for producing biodiesel fuel. In the preferredembodiment, the alcohol/catalyst mixer 22 comprises a 300 gallon mixingtank having a cone shaped bottom section. A representative tank 30 isshown in FIGS. 7A and 7B. The tank 30 includes a cone-shaped bottomportion 31 and a drain 32 located at the bottom. When used as a mixingtank or a reactor tank, the tank 31 advantageously includes mixinglooper jets 34 that function in a manner described below. Thealcohol/catalyst mixer 22 incorporates a similarly designed, butsmaller, reaction tank as that previously described for thetransesterification reactor. One advantage of the cone-shaped bottom isthat it allows the catalyst, which is typically in solid granular orflake form, to fall to the bottom and then be continuously recirculatedand mixed until it goes into solution with the alcohol. The size of thealcohol/catalyst mixer 22 is sufficient to produce the volume of mixedalcohol and catalyst for one of the separation reactors (about 20% ofthe volume of the separation reactor), although larger alcohol/catalystmixers may be used if increased efficiency is desired. The preferredalcohol/catalyst mixers and separation reactor tanks are manufactured byBryant Fuel Systems of Bakersfield, Calif.

The reactor unit preferably comprises one or more separation reactortanks 24 a, 24 b in which the transesterification reaction takes place.The reactor unit receives the alcohol/catalyst mixture from the mixingunit as a second feed, and the triglyceride source as a first feed, andcauses the transesterification reaction to occur. After sufficientcompletion of the transesterification reaction, the reactor unit outputsone or more streams comprising the reaction products of thetransesterification reaction, namely, biodiesel fuel (alkyl esters) andglycerin. In the preferred embodiment, the reactor unit comprises twoseparation reactor tanks 24 a, 24 b operating in parallel flowarrangement, i.e., each reactor tank receives independently controlledfeed streams and outputs an independent output stream.

The separation reactor tanks of the preferred embodiment are constructedand operate in a manner different from the batch processing reactortanks used in conventional biodiesel manufacturing processes. Theconventional batch reactors are uniform cylinders that use paddle mixersor other static mixing. The separation reactor tanks employed in thepreferred embodiment, on the other hand, are constructed having acone-shaped bottom portion 31 (see FIG. 7A) equipped with a drain 32 tofacilitate removal of the glycerin phase during the transesterificationprocess in order to provide a continuous process, unlike the prior art.The cone-shaped bottom portion and drain provided on the preferredreactor tanks facilitate this process. In addition, the preferredseparation reactors are provided with mixing looper jets 34 that providethe mixing action for the transesterification reaction. The jets areoperatively connected to one or more pumps (e.g., centrifugal or geardriven) that recirculate the reaction materials through the jets toprovide mixing. The jets are oriented such that, in combination with thedrain at the cone-shaped bottom of the tank, a vortex is created withinthe reaction tank to facilitate mixing of the materials to help drivethe transesterification reaction, thereby eliminating the need formixing paddles. The separation reactor tanks 24 a, 24 b are preferablyprovided with a double-wall construction having a gap (e.g. 2 inches)between the walls to provide a heat exchange media (e.g. heated water,dielectric oil, steam, or the like) to control the reaction temperature.In the preferred embodiment, each separation reactor tank isapproximately 1500 gallons in capacity and is approximately 8 feet indiameter and 8 feet in height in order to optimize the space constraintsof the modular production unit. Those skilled in the art will recognizethat, for example, the alcohol/catalyst mixing tanks and/or theseparation reactor tanks and their methods of use may alternatively bescaled up for use in large, fixed base operations in order to obtain theadvantages discussed herein in such a use.

In the preferred method of operation, the separation reactor tanks areoperated in a continuous mode, rather than a batch mode that is used inconventional biodiesel manufacturing processes. For example, theconventional biodiesel manufacturing process employs a first stagereaction of approximately four hours, after which the glycerin reactionproduct is drawn off, additional alcohol and catalyst are added, and asecond stage reaction is conducted for approximately two additionalhours. In the preferred mode of operation of the present invention, thetransesterification reaction is driven to sufficient completion in asingle stage within the reactor tanks, during which the reaction productstreams are continuously drawn off for the separation processesdescribed below. By using two or more separation reactor tanks, acontinuous flow of reacted material is provided to the remaining stagesof the production unit. The conventional biodiesel manufacturing processrelies upon two or more distinct batch operations, whereas the systemand method of the present invention advantageously provides forcontinuous removal of the glycerin as it is formed and forreintroduction of the alcohol/catalyst mixture. In a preferredembodiment, the temperature and/or pressure of the transesterificationreaction are increased to prevent the alcohol from boiling off and tothereby substantially decrease the reaction time. This option requiresthe plumbing, pumps, and tanks associated with the separation reactor tobe built to withstand the optimal increased pressure and/or temperature.In a further preferred embodiment, the entire process is nitrogenblanketed to reduce the risk of fire or explosion.

The separation unit comprises one or more components that are capable ofseparating the reaction products of the transesterification reaction. Inthe preferred embodiment, the separation unit comprises an array ofcentrifuge units 26 a-c, preferably three in number, connected inseries. The first centrifuge unit 26 a receives the output stream fromthe reactor unit, comprising the glycerin and alkyl esters along withunreacted alcohol. The first centrifuge unit 26 a separates the glycerinby-product and unreacted alcohol from the alkyl esters (biodiesel). Theglycerin and alcohol are initially stored in a first holding tank 140(see FIG. 4), and ultimately fed to the distillation unit, as describedbelow, or fed directly into the serial centrifuge units. The alkylesters cut from the first centrifuge unit 26 a is then fed as an inputto the second centrifuge unit 26 b, where it is combined with a heatedwash water and acid output stream from the third centrifuge unit 26 c,discussed below. The second centrifuge unit separates the water washphase from the alkyl esters, which are fed as an input to the thirdcentrifuge unit 26 c for a second acid/water wash. The hot water andacid wash expelled from the second centrifuge unit 26 b is initiallystored in a second holding tank 142 (FIG. 4), and ultimately pumped to awash water holding tank 148. The third centrifuge unit 26 c receives asa first input the alkyl esters cut taken from the second centrifugeunit, and, as a second input, a heated (e.g., 140° F.) mixture of washwater and acid routed from a water/acid storage unit 148. The acid/waterwash expelled from the third centrifuge unit 26 c is fed as an inputinto the second centrifuge unit 26 b, as explained above. The preferredacid is phosphoric acid, and the acid is used at a concentrationsufficient to neutralize the biodiesel reaction. The water/acidtemperature is preferably sufficient to maintain the resulting slurryjust under the boiling point of the alcohol. The third centrifuge unit26 c separates the alkyl esters, which is initially stored in a thirdholding tank 144, from the hot wash water and phosphoric acid, which isfed as an input to the second centrifuge unit, as described above. Thealkyl esters stored in the third holding tank are ultimately routed tosettling and/or storage tanks 150 for further processing as discussedmore fully below.

The centrifuge units used in the preferred embodiment are manufacturedby Costner Industries Nevada Corporation (“CINC”), of Carson City, Nev.Alternatively, conventional stacked disc centrifuge units may be used,such as those manufactured by Westphalia of Germany, Alfa Laval ofFrance, or Hutchison Hayes of Houston, Tex. The centrifuge unitspreferably incorporate a solids separation and self cleaning mechanism.Static mixers between the centrifuges may be used where sufficientmixing does not occur in the centrifuge units themselves. The CINCcentrifuges have been found to be superior in this regard because theydo not require static mixers and because they incorporate a clean inplace mechanism.

The distillation unit comprises one or more components that are adaptedto separate the materials contained in the by-product cut removed fromthe first centrifuge unit. In the preferred embodiment, the distillationunit is a continuous flow distillation unit 28 provided to separate thecrude glycerin product from the unreacted alcohol. A preferreddistillation unit is manufactured by Recycling Sciences, Inc. of Ramona,Calif. The continuous flow distillation unit 28 provides heating in thedistillation tank through a water or dielectric fluid jacket that may beheated by an external boiler and/or embedded heating elements. The flowof the glycerin and alcohol slurry is regulated by internal flowcontrols to provide sufficient mass heat transfer to raise the slurry toabove the boiling point of the alcohol but below the boiling point ofthe glycerin. Glycerin, with the alcohol removed, settles to the bottomof the distillation tank where it is transferred by a pump (e.g., geardriven) to an outside holding tank. In a preferred embodiment, heatrecovery units are used to transfer heat from the glycerin for use inother stages of the process, such as the separation reactors or the hotacid water wash.

Alcohol vapor is directed from the hemispherical cover of thedistillation tank to a cold water jacketed condensation coil to reducethe vapor to a liquid. The liquid alcohol is then routed to a holdingtank 128 from where it can be redirected to the alcohol/catalyst mixerfor reuse. In the preferred embodiment, the alcohol holding tank of thedistillation unit is maintained under a vacuum (preferably at 18 poundsof mercury or greater) to reduce the boiling point of the alcohol andincrease the thermal efficiency of the distillation unit. The alcoholholding tank is plumbed so that the vacuum is maintained throughout thedistillation system, including the distillation tank and thecondensation coil. In a preferred embodiment, the cover of thedistillation tank is hemispherical, the alcohol vapor recovery port isfitted with a splash guard, and the entire cover is removable to allowfor cleaning of the distillation tank.

In a further preferred embodiment, the distillation unit operates inconjunction with a float/level valve maintained in the first holdingtank 140. The preferred size and shape of the first holding tank is a 4foot cube (i.e., 4′×4′×4′), having a volume of approximately 64 cubicfeet. The first holding tank is provided with a float/level valve thatcontrols a pump that operates to feed the contents of the tank to thedistillation unit. As the tank level drops below a predetermined level,the float/level valve causes the pump to shut off, stopping the feedstream to the distillation unit.

The modular production unit 10 is preferably equipped with additionalauxiliary equipment to support the operation of the above-describedcomponents. For example, a boiler 42 and one or more heat exchangerunits 44 a, 44 b may be provided to heat water used as a heat exchangemedium for the reactor tanks. In addition, an air compressor 46 may beprovided to operate, for example, pneumatic pumps and mixers. Pumps 47are used for several functions within the systems and methods of theinvention, including flow transport and mixing. Still further, a controlunit 48 may be provided and equipped with any needed monitoring andcontrol equipment or devices, including temperature, pressure, pH, andflow measuring devices and readouts for each of the components of themodular production unit, flow controls for controlling the flow offeedstreams to each of the system components, and other controlequipment that may be necessary or advantageous to the operation of theproduction unit. The modular production unit may be made entirely energyand heat self-sufficient by operating a proper generator and boiler withbiodiesel produced by the modular production unit, thus allowing themodular production unit to operate in remote locations or areas wherepower service is expensive and/or unreliable.

The modular production unit is preferably incorporated onto a single ordouble platform, such as a skid mount, or into a housing 50, such as ashipping container, such that the system is easily shipped ortransferred to a remote site by either truck, rail, ship, or other meansof transportation, or operated in place on a truck trailer, rail car, orship. In a particularly preferred form, the modular production unit ishoused in a standard ISO Intermodal Shipping Container 50 havingdimensions of 8′×8′×40′. Thus, the components associated with thispreferred form of the modular production unit are of a size and shapethat may accommodated within the space limitations of the platform orhousing. A preferred orientation is shown in FIG. 2, in which a mixingtank 22, two reactor tanks 24 a, 24 b, an array of three centrifugeunits 26 a-c, a distillation unit 28, and a control room 48 are providedwithin a housing 50 comprising a standard ISO Intermodal Container. Thereactor tanks are generally cylindrical, and have a diameter and heightof slightly less than 8′ in order to fit within the confines of thehousing. Access to the mixing tank 22 and one of the reactor tanks 24 ais provided by an opening at the end of the housing 50 opposite thecontrol room 48, while access to the other components is provided by aworking space bounded by the other reactor tank 24 b, the centrifugeunits 26 a-c, and the distillation unit 28, the latter two of which areset against one of the long walls of the housing. Access to the tops ofthe reactors is provided by hatches cut into the container 50 in whichthe reactors are housed, and manways incorporated into the tops of thereactors. The hatches also provide space for pressure relief vents andemission control equipment as needed.

Although several advantages are obtained by providing the systems andmethods described herein in a self-contained, modular production unit,those skilled in the art will recognize that one or more of thedescribed system components may be provided in a scaled up form for usein a fixed base, nonmodular configuration to obtain the other advantagesprovided by those components.

In a still further preferred systems and methods of the presentinvention, the above described modular production unit 10 is combinedwith additional fixed and/or removable equipment and components in abiodiesel processing plant 60, as shown in FIG. 3. The biodieselprocessing plant 60 preferably includes a modular production unit 10, asdescribed above. The plant 60 also includes a processing unit 62, whichprovides processing of the raw material inputs and finished outputs fromthe modular production unit, as described more fully below. Thepreferred plant further includes storage facilities, including analcohol storage unit 64, a triglycerides storage unit 66, a finishedproduct (biodiesel) storage unit 68, a glycerin storage unit 70, and awash water storage unit 72. In a particularly preferred form, thealcohol storage unit, triglycerides storage unit, glycerin storage unit,and wash water storage unit each comprises a 10,000 gallon storage tank,while the finished product (biodiesel) storage unit comprises a 20,000gallon storage tank. The plant is optionally provided with awash/containment area 74 to accommodate accidental spills.

The processing unit performs two primary functions. First, it providesequipment and functionality to process the triglycerides raw feedstockprior to introducing the feedstock into the reactor unit of the modularproduction unit. Second, it provides equipment and functionality toprocess the biodiesel finished product produced by the modularproduction unit.

In the preferred embodiment, the raw materials processing is performedby a pair of settling tanks 80 a, 80 b and a coalescing basket filter82. The preferred raw materials processing also, optionally, includes ahot box member described in more detail below. The preferredtriglycerides feedstock is any organic fat or oil, including virginvegetable oils such as soy, canola or cottonseed, as well as recycledoils, such as used fryer oil and grease trap materials, or animal fats,such as lard or beef tallow. Many of these materials, particularly therecycled oils, will have impurities, including coarse particulates andwater. The water impurities may be in the form of bulk water, entrainedwater, or microemulsions. The triglycerides feedstock is fed as an inputto the coalescing basket filter 82, where the feedstock is filtered toremove particulates and/or water. The filtered feedstock is routed toone of the settling tanks 80 a, 80 b, where it is stored until needed asfeed to the reactor units of the modular production unit. The settlingtanks are preferably heated (e.g., to at least 120° F.) and are providedwith cone-shaped bottom portions and drains to promote settling andfacilitate removal of waste and particulates. Such waste andparticulates are advantageously removed by directing the output flowfrom the bottom drain through an additional coalescing basket filter offiner mesh prior to being transferred to the separation reactor tanks.

Additionally, the settling tanks 80 a, 80 b may be optionally fittedwith one or more metering pumps for delivering acid (such as phosphoricacid or sulfuric acid) which, in combination with heat, assists inbreaking up emulsions (particularly in grease trap material) andfacilitates the phase separation of the water and fats/oils/greases.Once the water is drained off, additional acid may be added to convertfree fatty acids to fatty acids that can be more easily converted intoalkyl esters. The acidified fats/oils/greases can then be reacted withalcohol as a first step in the separation reactors (i.e. acid catalysis)followed by a reaction with the alcohol/catalyst mixture (i.e. basecatalysis) to more efficiently produce alkyl esters from high free fattyacid feedstocks such as grease trap materials.

Also in the preferred embodiment, the biodiesel finished productprocessing is performed by a series of four biodiesel settling tanks 84a-d, two salt dryers 86 a, 86 b, and an automated filter system 88. Theprimary function of the biodiesel finished product processing is toremove water, either in the form of bulk water, entrained water, ormicroemulsions, from the finished biodiesel product. Each of thesettling tanks 84 a-d is provided with a cone shaped bottom having adrain to facilitate removal of water that has settled out of thebiodiesel product. The biodiesel product may also be fed through thesalt dryer 86 a-b, which functions by directly absorbing the watercontained in the biodiesel finished product, and/or by causing the watercontained in the product to become heavier due to salt absorption, andtherefore more readily removed by settling in the settling tanks. As anadditional option, a dehazing compound may be added to the biodieselfinished product in the settling tanks. The dehazing compound causessmall water droplets to agglomerate and settle out of the biodieselproduct to the bottom of the settling tanks, where it is removed throughthe drain.

The automated filter system 88 serves as a fail-safe to prevent flow ofbiodiesel product that contains greater than the maximum amount of waterdesired, and preferably comprises a combination of a salt filter, acoalescing filter, a clarification filter, and a gel filter. In apreferred embodiment, the filtering system is automated to sense waterbuild up in the first stage salt dryer and the second stage coalescingbasket filter, and to sense back pressure caused by the build up ofimpurities in the entire system. In a further preferred embodiment, thethird stage filters are 10 to 30 micron glass filters, and the fourthstage filters are a 10 to 2 micron gel filter composed of corn starchpolymer embedded paper elements. In a still further preferredembodiment, the entire filtering system is designed to recirculate thebiodiesel in the settling tanks, and incorporates sight glasses andsampling valves for obtaining biodiesel samples for testing prior to thebiodiesel being transferred to the final distribution tank. In yetanother embodiment, the filtering system is fitted with a meteringsystem which allows for the introduction of additives to the biodieselin the necessary ratios. Preferred additives include those speciallyformulated for biodiesel (e.g., by Betz Dearborn of Woodlands, Tex.) forcold flow suppression, oxidative/thermal stability, NOx reduction,and/or dehazing. This system allows for the custom blending of biodieselwith additives to meet the specification of a variety of end users underdifferent climatic and operating conditions.

In a particularly preferred embodiment, the processing unit isincorporated onto a single or double platform, such as a skid mount, orinto a housing, such as a shipping container, such that the processingunit is easily shipped or transferred to a remote site by either truck,rail, ship, or other means of transportation, or operated in place on atruck trailer, rail car, or ship. In this manner, both the processingunit and the modular production unit are able to be easily shipped andlocated to a desirable location near a feedstock source, or near the endusers.

The interrelationship of the above components that comprise thebiodiesel processing plant are illustrated in FIG. 3. The alcoholstorage unit 64 is connected by a suitable flow path 102 to the mixingunit contained in the modular production unit. The triglycerides storageunit 66 is connected by a suitable flow path 104 to each of thefeedstock settling tanks 80 a, 80 b contained in the processing unit.The feedstock settling tanks, in turn, are connected by a suitable flowpath 106 a, 106 b to the reactor units 24 a, 24 b contained in themodular production unit. The output of the distillation unit 28contained in the modular production unit is connected by a suitable flowpath 108 to the glycerin storage unit 70. The output of the secondholding tank 38 contained in the modular production unit is connected bya suitable flow path 110 to the wash water storage 72. Finally, theoutput of the third holding tank 40 contained in the modular productionunit is connected by a suitable flow path 112 to the biodiesel finishedproduct settling tanks 84 a-d contained in the processing unit 62.

The preferred biodiesel manufacturing and processing method of thepresent invention is illustrated in the process flow chart shown in FIG.4. As shown, the triglycerides feedstock raw materials 120 are fed in astream through a filter 122 to the two settling tanks 124 a, 124 bconnected in parallel flow arrangement. The outputs of the two settlingtanks are connected through a pair of strainers 126 a, 126 b to providea first input stream to a pair of reaction tanks 136 a, 136 b. Analcohol tank 128, sodium hydroxide tank 130, and sulfuric acid tank 132provide input feed streams to a mixing tank 134, where the materials aremixed prior to feeding the mixture as a second input stream to the pairof reaction tanks 136 a, 136 b, where the transesterification reactiontakes place. Alternatively, the alcohol and catalyst feeds may be routedto an inline static mixer in place of the alcohol/catalyst mixing tank134.

The reaction product stream from the reaction tanks is fed as an inputto the first centrifuge unit 138 a contained in the centrifuge array.The glycerin output stream from the first centrifuge unit is fed to theglycerin holding tank 140, while the alkyl esters stream is fed as afirst input to the second centrifuge unit 138 b. The second centrifugeunit receives a wash water/phosphoric acid output stream from the thirdcentrifuge unit 138 c as a second input stream. The second centrifugeunit 138 b has two output streams; the first, comprising wash water andphosphoric acid, is fed to a wash water holding tank 142, while thesecond, comprising a washed stream of alkyl esters, is fed as a firstinput to the third centrifuge unit 138 c. A wash water and phosphoricacid supply tank 141 provides a second input stream to the thirdcentrifuge unit 138 c. The first output stream of the third centrifugeunit comprises wash water and phosphoric acid, which is fed as an inputto the second centrifuge unit 138 b, as discussed above. The secondoutput stream of the third centrifuge unit comprises washed biodiesel,which is fed initially to a biodiesel holding tank 144. Alternatively,additional centrifuge units may be added to provide additional orvariable cuts of the glycerin stream, and/or additional or fewercentrifuge units may be used for the water wash phase.

The glycerin reaction product and unreacted alcohol contained in theglycerin holding tank 140 is fed as an input stream to the distillationunit 146, which separates the stream into a crude glycerin productstream, which is fed to a glycerin storage tank, and an unreactedalcohol stream, which is returned to the alcohol feed storage tank 128for use in the transesterification reaction. Water, unreacted oil,and/or biodiesel which phase separate in the holding tanks may beredirected for further processing in the modular production unit.

The wash water contained in the wash water holding tank 142 associatedwith the second centrifuge is fed to a larger wash water storage unit148 for later disposal. Glycerin, unreacted oil, and/or biodiesel whichphase separate in the holding tanks may be redirected for furtherprocessing in the modular production unit.

The washed biodiesel product contained in the biodiesel holding tank 144is fed to a biodiesel settling tank 150, where water and otherimpurities are removed by the processes described above. A finalfiltering process 152 is provided to ensure that the biodiesel productcontains less than 500 ppm of water. An air compressor 154, heater 156,and power generator 158 provided auxiliary functionality to the process.

In a yet further preferred embodiment of the present invention, animproved system and method for providing raw triglyceride feedstock isprovided. A particular preferred feedstock comprises used fryer oil,such as that produced by commercial food establishments such asrestaurants and hotels. The conventional system of collecting such oilsconsists of transporting the used oil in an open cooking pot or the liketo a disposal drum or container that is periodically collected by adisposal service. This system frequently results in oil spills that cancause burn injuries and/or slip and fall injuries to workers operatingthe equipment. Turning to FIGS. 5A-5C, the system and method of thepresent invention, on the other hand, includes the use of a smallcovered drum 170, typically 30 gallons or less. The drum is providedwith wheels 172 attached to its bottom surface, such as, for example, bya welded frame 174 having casters. These roller drums can be easilymaneuvered in the confinement of a restaurant kitchen. The hot usedfryer oil is transferred from the fryer into the roller drum and thenthe roller drum is sealed and wheeled to the disposal location, where itis left in the roller drum, rather than transferred to a separatecontainer. The roller drums are then either picked up and exchanged forclean empty roller drums, or pumped out by a disposal service intolarger containers on a disposal vehicle, thereby eliminating the needfor transferring hot used fryer oil into open containers and reducingthe amount of handling necessary.

The preferred roller drum includes a removable lid 176 for ease ofcleaning and maintenance, and a small bung hole 178 in the lid for safetransfer of the hot used fryer oil from the fryer into the roller drum.It is further preferred to provide a bottom frame 174 (to which thecasters or wheels are connected) that is slightly wider than the drum,in order to provide greater stability. It is also preferred to provide3″ wheels (or larger) on pivoting casters attached to the frame at fourequidistant points to provide for greater maneuverability.

Once the used fryer oil has been collected and placed in the rollerdrums, the fryer oil must be heated and filtered prior to converting itinto biodiesel. The initial objective is to heat the used fryer oil tomake it liquid enough to remove water and particulates. Many of the usedfryer oils are solid or too viscous to filter at temperatures as high as70° F. Conventional heating and filtering processes consist of steaminjection or belt heaters for the drums. These processes are energyinefficient and not suitable when the above-described roller barrels areused. Accordingly, in a further preferred embodiment shown in FIGS. 6Aand 6B, the present invention includes a liquid tight hot box 180 with ahinged lid 182 into which pipes 184 are configured to support the rollerbarrels in an inverted position, and to circulate hot water (at least120° F.) or steam, both in the roller barrel support grid and at thebottom of the hot box. The roller barrels are small enough that a singleoperator is able to tip the barrels into an inverted position to feedthe hot box. The hot box is preferably of a size sufficient toaccommodate three or more roller barrels and their contents. A pivotinghoist (not shown) may optionally be provided to lift and invert theroller barrels for placement on the hot box.

A fine mesh screen 186 (e.g., “¼ inch” mesh) is placed over the rollerbarrel support pipes 184 to remove coarse particulates (e.g., papertowels, french fries, etc.). The mesh is preferably removable so that itcan be easily cleaned. When inverted, the roller barrels empty theircontents onto the mesh screen 186 and the heated support pipes 184,which causes the used fryer oil to become less viscous, thus allowing itto pass through the mesh screen and onto the heater pipes below. Coarseparticulates are left on the surface of the mesh screen and these can bescraped off for removal, or the mesh screen can be removed and cleaned.

An outlet for the heated and filtered oil is located at least 2″ off thebottom of the hot box so that finer particulates and water are allowedto settle. The outlet oil is pumped through a finer mesh (e.g., 125micron) coalescing basket filter to further remove water andparticulates. The filtered oil is pumped from the hot box into thefeedstock tanks.

In the preferred embodiment, the hot water or steam is generated by aboiler running on biodiesel, used fryer oil, or glycerin. The hot box ispreferably of sufficient size to allow for processing at least 20 rollerbarrels per hour, and may be used in multiple configurations or largersizes to accommodate larger volumes. The hot box 180 may be insulated,and solar, electric, or conventionally fueled heaters may be analternative source of generating hot water or steam.

While various preferred embodiments of the invention have been shown forpurposes of illustration, it will be understood that those skilled inthe art may make modifications thereof without departing from the truescope of the invention as set forth in the appended claims includingequivalents thereof.

1. A biodiesel production unit comprising: a reactor unit, a separatorunit downline in a flow path from said reactor unit, and a distillationunit downline in a flow path from said separator unit, wherein saidreactor unit, said separator unit, and said distillation unit areincorporated onto a transportable platform or into a transportablehousing.
 2. The biodiesel production unit according to claim 1, whereinthe separator unit comprises an array of three centrifuge unitsconnected in series.
 3. The biodiesel production unit according to claim1, wherein the distillation unit comprises a continuous flowdistillation unit.
 4. The biodiesel production unit according to claim1, wherein the reactor unit comprises a reactor tank having acone-shaped bottom portion.
 5. The biodiesel production unit accordingto claim 4, wherein said reactor tank includes a pump driven nozzle jetadapted to provide mixing of the contents of said reactor tank.
 6. Thebiodiesel production unit according to claim 1 further comprising amixing unit upline in a flow path from said reactor unit.
 7. A biodieselprocessing plant comprising: a biodiesel production unit comprising areactor unit, a separator unit downline in a flow path from said reactorunit, and a distillation unit downline in a flow path from saidseparator unit, wherein said reactor unit, said separator unit, and saiddistillation unit are incorporated onto a first transportable platformor into a first transportable housing, and a raw materials processingunit upline in a flow path from said biodiesel production unit, said rawmaterials processing unit comprising a raw material settling tank forremoving impurities from feedstock materials, and a filtration unit. 8.The biodiesel processing plant according to claim 7 further comprising afinished product processing unit downline in a flow path from saidbiodiesel production unit, said finished product processing unitcomprising a finished product settling tank for removing impurities froma finished biodiesel product, and a filtration unit.
 9. The biodieselprocessing plant according to claim 8 wherein said raw materialsprocessing unit and said finished product processing unit areincorporated onto a second transportable platform or into a secondtransportable housing.
 10. The biodiesel production unit of claim 1,wherein said reactor unit comprises at least two reaction tanks.
 11. Thebiodiesel production unit of claim 10, wherein each of said reactortanks has a cone-shaped bottom portion having a drain located at or nearthe bottom of the bottom portion.
 12. The biodiesel production unit ofclaim 11, wherein each of said reactor tanks is provided with a heatexchanger.
 13. The biodiesel production unit of claim 1, wherein saiddistillation unit comprises a continuous flow distillation unit.
 14. Thebiodiesel production unit of claim 13, further comprising an alcoholholding tank connected to an output of said distillation unit, whereinsaid alcohol holding tank and said distillation unit are maintainedunder a vacuum.
 15. The biodiesel production unit of claim 1, furthercomprising: a feedstock heater, a feedstock filter, a feedstock waterremoval unit, and a mixing unit, wherein said heater, said filter, saidwater removal unit, and said mixing unit are incorporated onto thetransportable platform or into the transportable housing upstream fromsaid reactor unit.